Messages in this thread | | | Date | Thu, 10 May 2007 16:12:11 +0200 | From | Tomasz Chmielewski <> | Subject | RE: [PATCH 00/16] raid acceleration and asynchronous offload api for 2.6.22 |
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Ronen Shitrit wrote:
> The resync numbers you sent, looks very promising :) > Do you have any performance numbers that you can share for these set of > patches, which shows the Rd/Wr IO bandwidth.
I have some simple tests made with hdparm, with the results I don't understand.
We see hdparm results are fine if we access the whole device:
thecus:~# hdparm -Tt /dev/sdd
/dev/sdd: Timing cached reads: 392 MB in 2.00 seconds = 195.71 MB/sec Timing buffered disk reads: 146 MB in 3.01 seconds = 48.47 MB/sec
But are 10 times worse (Timing buffered disk reads) when we access partitions:
thecus:/# hdparm -Tt /dev/sdc1 /dev/sdd1
/dev/sdc1: Timing cached reads: 396 MB in 2.01 seconds = 197.18 MB/sec Timing buffered disk reads: 16 MB in 3.32 seconds = 4.83 MB/sec
/dev/sdd1: Timing cached reads: 394 MB in 2.00 seconds = 196.89 MB/sec Timing buffered disk reads: 16 MB in 3.13 seconds = 5.11 MB/sec
Why is it so much worse?
I used 2.6.21-iop1 patches from http://sf.net/projects/xscaleiop; right now I use 2.6.17-iop1, for which the results are ~35 MB/s when accessing a device (/dev/sdd) or a partition (/dev/sdd1).
In kernel config, I enabled Intel DMA engines.
The device I use is Thecus n4100, it is "Platform: IQ31244 (XScale)", and has 600 MHz CPU.
-- Tomasz Chmielewski http://wpkg.org
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